Gas Mileage: 454

[gary19734]

Kev first chance to get back to you your motorhome is the same as mine except 4 feet longer when i was having trouble with manifolds over heating i taped card board all around motor and used inspection camera drove down rd.when motor home went over 35 miles per hour all air pulled away from motor.The wheel wells on these are a piss poor design and there isnt a firewall air goes through radiator then splits to the far right and left of motor right down the outside of the frame rails.I would have a metal spacer welded to your stock air cleaner also saw on your other posts that you still had charcoal spark arrester in air cleaner pry that piece of junk out of there, you will never get air with that junk.One last thing i know that this is  another big expense but edelbrocks don't work all that well unless there mated with with a edelbrock manifold completely different design from the q jet manifold.but then again Chevy's will run with just about anything.Read up on the distributor upgrade i told you about it completely changes the timing curve witch gives you power through the entire range.  One more dumb thing check your fuel it could be the whole problem there selling some real garbage out there next to water.  Have a good trip Gary

[ClydesdaleKevin]

Hip hip horray!!!
After installing an Edelbrock 1411 carburetor with a spread bore adapter and using the stock air cleaner, I was getting about the same poor gas mileage as the messed up Rochester Quadrajet.

I drove from St. Mary's Georgia to Hammond, LA, and averaged 5.9 mpg...ye gads!!!  It was time for some extreme measures!

I took out EVERY unnecessary vacuum line, leaving only the ported vacuum line to the distributor advance, the big vacuum line to the PCV valve, and the full time vacuum line has only one connection to a steel line that goes under the engine, which I imaging has to do with the transmission...I left that one on there.

Pulled out every AIR hose except one from each pump, which I left attached to the manifold AIR boxes.
Pulled out the EGR valve and used a block of plate and gasket.
Removed the hose and gasket from the passenger side valve cover and installed an Edelbrock breather.
And finally, installed a 3 inch high by 14 inch Edelbrock open element air cleaner.







Once all these changes were made, I started the engine and let it fully come to temperature, and the idle was now 1000 rpm instead of 700!

I adjusted it down to 700, and then adjusted the idle mixture screws to the side of lean...easy to do on an Edelbrock, just turn them in slowly until the idle drops, then back them out 1/2 turn.  Both screw heads even ended up in the exact same position...gotta love Edelbrocks!

Then I had to increase the idle a bit, since it had dropped to about 650.

I revved the engine, and it droppped to a steady 700 rpm immediately , and for the first time since owning this RV, there was no fluctuation at all in the idle no matter how many times I revved it.

The real test was today's road test!

The first part of the trip was out of the campground in Hammond, Louisiana, and then I-12 West, then I-10 West, almost to the Texas border where we had to stop for gas, since we started out with just at a quarter tank.  We recorded the mileage, how many gallons used...and holy crap!!!

8.8 mpg!!!

Okay, maybe a fluke, or a miscalculation...we set the odometer trip meter to zero, and kept heading West.  When we pulled into a Flying J tonight, exit 789 just east of Houston, I filled up again, and recorded the gallons to fill it up.  Divided the miles by the gallons, and it was

8.5 mpg!

The first figure was an estimate, since we didn't know exactly how many gallons had been used out of the tank before all the vacuum line and air cleaner changes had been made.  The guage was reading 3/4, so we subtracted 15 gallons from what it took to fill up the RV and came up with that figure or 8.8.

The 8.5 is no crap dead reckoning!

HECK yeah!

And there is no lack of power now!  This thing runs better than it ever has before.  It wants to fly up the hills, but I keep her back to save gas.  Almost every single hill/bridge was taken at 50mpg without opening the secondaries!!!    Had I wanted to open up the secondaries, she immediately accelerates up the hills, but for the sake of good gas mileage, I kept the pedal light!

The only bridge where I had to open the secondaries to make the hill at 45mph...and by the time she reached the top she was doing 55...was the big high and long bridge coming out of Baton Rouge, LA.  That's one heck of an incline, so I had to open them up.

This mileage was achieved also in part to a very light foot on the pedal, keeping her at 55, patiently taking the steep hills at 50 so the secondaries wouldn't open, and accelerating slowly...no need to get there fast!  A couple of other times I had to open up the throttle and let the engine have her power, and both times it was because of some idiot on a cell phone coming up an on ramp and not paying attention to the big RV about to turn them into scrap metal.

Okay, so enough rambling.  A solid 8.5 mpg after all the mods I made, with great power up the hills, and smooth quiet performance on the flats.  I ain't gonna complain about that!

Kev

[Oz]

From that improvement, it won't be long at all until you've recouped the cost of the changes and then, feel your wallet staying heavier at the pumps!

   

[gary19734]

Kool sounds like you earned it.Read your plugs one time if there lite gray a little more towards the dark side your not running too lean enjoy   Gary

[ClydesdaleKevin]

Thanks Gary.  With Edelbrocks, those screws only effect idle mixture...lean it out and you won't burn as much fuel at stop lights and stop signs or in gridlock traffic.  Pretty much all they do.  If you want to go richer or leaner on an Edelbrock at speed, you have to replace metering rods and jets and springs...which I don't plan on doing at all with the mileage we are getting!


Kev

[ClydesdaleKevin]

Mileage report updated:

Got an incredible 8.5 mpg all through Houston...and then it got hillier.  We were leaving sea level, and its all uphill from here!

Calculated the latest mileage at our latest fuel stop in San Antonio, TX.  Elevation gains from now on all the way to Arizona!  Long rolling hills...had to open the secondaries on a couple hills to maintain highway speed.

Still getting an average of:  7.37 mpg!!!

Can't complain about that, especially since I was keeping an average steady speed of 50-55mph unless I was coasting downhill as fast as she wanted to go!

And Gary, great idea about the inspection camera!  That got me to thinking...a webcam and a strong light positioned just right and aimed at well painted timing marks sure would make a one-man timing adjustment a lot easier!

Kev

[ClydesdaleKevin]

I found out, through reading the book RV RX for Performance, that gas engines get the best fuel economy at around 38 mph (standard gearing)...go figure! 

Since at higher elevations my fuel economy dropped down to about 7 mpg, I decided to try it out, taking back roads and highways recently from Tombstone, AZ to Safford, AZ, and from Safford to Hot Wells Dunes, and sure enough, my MPG went from around 7mpg, to 10+ mpg!  I can definitely live with that!  I kept it to right around 40mph, coasting down the mountains, easy on the pedal, and avoided opening the secondaries whenever possible.  Sure made the trip more pleasant too...you can actually enjoy the scenery at 40!

There were lots of steep climbs, but rambling along at 40mph was pretty easy to do.  I'll let you all know how she does on the next leg of our journey...Hot Wells Dunes to Apache Junction, AZ, about 100 miles on Route 70 to Hwy 60 and some pretty steep inclines and declines.  I'll also be able to keep the speed down on these roads, so I'll update this report in a couple of weeks.

Kev

[Oz]

That book is available in the Club Store - It's loaded with all kinds of great information and it's written so even the least mechanically inclined individual (like me) can undertand it completely!  It also covers simple, cheap fixes for known, common problems with all the major brand chassis!

http://www.classicwinnebagos.com/forum/index.php?action=store;sa=view;id=184

This is a very valuable yet highly overlooked publication which I recommend to everyone.  No matter how much you may know, you'll definitely learn more from this book!

[HandyDan]

This must be some book.  I looked it up on Amazon.com and found you can still get a new copy for $110.  But, Barnes and Noble wants closer to $300 for it.  I happened to find a hard back copy in like new condition for 75cents at BargainBooks.com.  However, it costs $4.00 shipping.  I can't wait for it to arrive.

[ClydesdaleKevin]

Its a good read too.  The authors take the time to explain everything in a way that makes it a nice read...technical enough so you don't feel like they are talking to an idiot...but simple enough that anyone can understand what they are talking about.

I'd love to have a hard copy some day (to read outside on the porch, etc.) but the club store here has it for 8 bucks, so its hard to beat!

Worth every penny!

Kev

[DonD]

Just filled up. 50-50 city/hwy. I have recently removed the carbon filter thingy in the OEM air cleaner housing. hopefully helping  my KN get more air.

Did something right..8.9 mpg!

[ClydesdaleKevin]

Awesome Don!  Our next voyage is from Apache Junction, AZ, up to Sedona, taking I-17.  I have been told the elevation gain is gradual along I-17, but I'm very curious what our gas mileage will be climbing on a highway where I have to try to maintain 55mph.  I'll let you all know in a few days once we reach Sedona!

Kev

[jackd40]

I did a lot of the "fixes" that have been mentioned in this tread; including the ones that you wouldn't think would improve mpg.  Like, 4 new bilstein shocks and steering damper, replaced the front airbags and two in the rear, rebuilt the quadrajet, replaced all vacuum lines, changed the oil and tranny fluid.  Put 60 pounds of air in the tires.  Filled up the water tank, propane and a full tank of gas.  Drove from Meridian ID. to Silver City ID. a 132 mile round trip.  Never exceeding 60mph. No wind rolling hills. 

I got 8.3 mpg. Lucky I guess.

[DonD]

My last 5 fill ups avg is 8.1!   The last tank was up and down I-17 to SR 260 to Dead Horse Ranch State Park pulling my Tracker on a trailer, the mpg was 7.6.

Heading out Fri. for a 2 nighter. the route has some long climbs and I will be dragging the same set up, hope my avg doesn't dip... too much.

8/2/13    7 tank avg= 7.55. All trailer/dolly miles, lots of hills. In Sept we plan to do Grand Canyon w/o towed. Stay tuned.

[DonD]

8 tank avg...8.3.

[DonD]

Some of my earlier mileage figures were based on incorrect info. from a GPS that when compared to a new Garmin, was a bit off. Subtract about 10 percent  I thought the odo. was off...isn't after all.

With my new unit (matches map and odo. miles) my MPG is about like everyone elses....About 7. I did get 10 on a short run (90mi) with 2500lb 4x4 on 14ft car trailer on FLAT roads.
My last 4 tanks avg. is 7.3, excluding the 10 mpg run...that's too short really.

"Takes what it takes"!!

[Stripe]

Poop. When was last tune-up done?

[ClydesdaleKevin]

Averaging very low 7s lately, but the K5 Blazer is 900 lbs or more heavier than the old Jeep YJ, and the rear suspension shock mounts on the RV were broken.  Gonna fix the mounts before our next trip to Oklahoma in April, and I'll let you all know what it is then.  If its not much of an improvement, then it might be the intake I installed restricting air...might have to do a double snorkel intake.  Or headers.  Or both...lol! 

Kev

[DonD]

The last tune up WILL be done soon (None done since I've owned her)

EDIT: The number 8 plug boot was melted. I used 2 gal. more last trip than the same trip in October and this time I was towing about 1000lbs less wt. Now I know why it used more and didn't seem "quite right". I haven't found an OEM boot cover so off to Napa tomorrow for a new aftermarket one and a new neutral sw. The wire was not making contact, as I pulled the boot it came apart.

[legomybago]

The in-laws last trip a couple weeks ago...averaged 6.75 mpg, staying at 55 mph's, towing a 2,800 car. We were happy, it's been as low as 5.75 in the past. How much more you really going to get with a stock 454, pulling 15k? If your getting 7 +, Thats great!!

Someone on this site a few weeks ago said "I just figure on 30 dollars an hour to operate the rig"....thats pretty right on.

[DonD]

Yup...50 cents per mile.

[pvoth1111]

I always figure its a dollar a mile....as its not just gas  that gets ya down the road....

[engineer bill]

On our new (to us) 1989 Winne Warrior (454 carb) we had calculated an average mpg of 5.5 mpg in mixed highway (55-60 mph) and secondary/curvy/hilly roads over six tanks of gas. After reading some of the suggestions here, the easiest suggestion seemed to be to to adjust the parking brake. (This despite the fact that I had paid the shop to do this three months ago.) So I parked on a small hill and set the parking brake. Transmission in neutral and slowly let my foot off the brake. It didn't move. So I started loosening the adjustment which is right there on the p brake handle. I must have turned it twenty times before the p brake started to release. I continued to loosen it by two turns. Then I started turning it back tighter by about a half a turn at a time until the brake held the RV on the hill. Then I turned one more half turn.

Subsequently, on the trip just completed yesterday from Martinez CA up to Salt Point State Park and back, (about 250 miles) the mpg was 7.8 mpg. (mixed highway (55-60 mph) and secondary/curvy/hilly/very narrow roads) and an imaginary egg between my foot and the gas pedal.

There are a number of other things I want to look at re. mileage but this one small thing is going to save me $$$. Thanks everyone.

[cncsparky]

I finally got a road trip out of mine last weekend  .  About 200 miles and averaged 6.96 .  Fairly flat terrain here in Ks  W%   and pulling my boat around 3500 lbs.  Planning to lean out the primary side of my QJ, but won't get to that till this fall probably.  Will have a 520 mile round trip in a few weeks.

[Rickf1985]

I just filled up after our Labor day trip and YEE HAW! 11 MPG while towing a trailer! That was filling up at the beginning of Rt. 29 in Virginia and going down to Syria and then back to NJ while towing a trailer with a 4'000 lb. Jeep on it. Trailer and Jeep about 6,000 lbs.. I couldn't believe it so I ran the route through he GPS to be sure the mileage was correct and it was. I still have the touch.